dccp: Allow to distinguish original and retransmitted packets

This patch allows the sender to distinguish original and retransmitted packets,
which is in particular needed for the retransmission of DCCP-Requests:
 * the first Request uses ISS (generated in net/dccp/ip*.c), and sets GSS = ISS;
 * all retransmitted Requests use GSS' = GSS + 1, so that the n-th retransmitted
   Request has sequence number ISS + n (mod 48).

To add generic support, the patch reorganises existing code so that:
 * icsk_retransmits == 0     for the original packet and
 * icsk_retransmits = n > 0  for the n-th retransmitted packet
at the time dccp_transmit_skb() is called, via dccp_retransmit_skb().
 
Thanks to Wei Yongjun for pointing this problem out.

Further changes:
----------------
 * removed the `skb' argument from dccp_retransmit_skb(), since sk_send_head
   is used for all retransmissions (the exception is client-Acks in PARTOPEN
   state, but these do not use sk_send_head);
 * since sk_send_head always contains the original skb (via dccp_entail()),
   skb_cloned() never evaluated to true and thus pskb_copy() was never used.

Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>

1 files changed, 1 insertions, 1 deletions

diff --git a/net/dccp/dccp.h b/net/dccp/dccp.h
index 743d85fcd651..1c2e3ec2eb57 100644
--- a/net/dccp/dccp.h
+++ b/net/dccp/dccp.h
@@ -226,7 +226,7 @@ static inline void dccp_csum_outgoing(struct sk_buff *skb)
 
 extern void dccp_v4_send_check(struct sock *sk, int len, struct sk_buff *skb);
 
-extern int  dccp_retransmit_skb(struct sock *sk, struct sk_buff *skb);
+extern int  dccp_retransmit_skb(struct sock *sk);
 
 extern void dccp_send_ack(struct sock *sk);
 extern void dccp_reqsk_send_ack(struct sk_buff *sk, struct request_sock *rsk);